Bittersweet
by Crystalized Flowers
Summary: The fortune-teller told them of futures that would drastically change their peaceful lives. Ten years later, he still willingly sacrifices everything for him. And he knows that it had been his choice. That's why, when watching the happy couple under the cherry blossoms, his smile isn't angry, but bittersweet. Reiji x Ai, One-sided Aine x Reiji.
1. Part 1

**A/N:** So, the first part is also cross-posted in my UtaPri one-shot series Hearts Intertwined as the fourth one-shot "Sacrifice," but the second part (which turns this story into ReiAi) isn't. This is based off a prompt I found on tumblr. The prompt will be posted at the bottom of the second part so you aren't spoiled ;)

Enjoy~ More notes will come at the bottom of the second part.

 **Disclaimer:** I do not own Uta no Prince-sama or the plot, just what I wrote. I also _do not_ own the cover, I think the original source was featherblessings on tumblr.

* * *

 **~~Bittersweet~~**

 **by Crystalized Flowers**

Part One

"Aine! Look!" At their elementary school festival, Reiji points to a crowded booth where a mysterious woman smiled underneath her veil. "Why is everyone gathering there? Let's go check it out!"

"Reiji, wai-" The cyan haired boy tries to protest, but he is eventually dragged over to the fortune-teller by his cheerful brunette best friend. The two children join the crowd, Reiji standing on his tip-toes to peer over the taller kids, and Aine narrowing his eyes at the woman. With her lilac veil and her strange goldenrod eyes, she was simply suspicious. Her kind smile seemed to be deceptive and her coral hair is tied back.

"Who is she?" he mutters underneath his breath.

"You don't know?" He turns to glance at the small red-headed girl standing next to the booth, holding a basket filled with an assortment of potions. Her crimson eyes blink at him innocently as she tilts her head to the side, allowing some of her wavy red hair to fall across her face. "Haruka-nee is a well known witch. She can cure diseases, tell futures, remove curses, and perform magic." The girl smiles. "She's amazing."

Just as he opens his mouth to answer the girl, the woman - Haruka, it seems - finishes up with her booth. "Sorry, dears, but I have to go. I have to move on to the next town. Maybe next time." She adds to some young children who were whining about getting their fortunes told. "Let's go, Tomo-chan." She places her crystal ball in the girl's basket and begins walking away.

"A-ah! Coming, nee-san!" The girl struggles slightly with the heavy basket as she hurries after Haruka. Reiji's natural kindness causes him to swoop in and take the basket from her, surprising Aine.

"Let me help!" He winks at her, running off after Haruka.

"Ah, thank you!" The girl follows after him, Aine not far behind. Geez, what a troublesome best friend he had to look after.

By the time they reached the school gates, Haruka was already waiting there, unsurprised to see the two boys carrying the basket together, Tomo standing close to them. She smiles softly, kneeling down to the children's level. "Thank you, darlings. As thanks, would you like for me to tell your fortunes?"

Aine is still wary, but Reiji lets out an excited "Yes!".

Seeing Aine's hesitation, Haruka chuckles and takes his hand first, catching him off guard. He blinks at her with his large cyan eyes as she closes hers, concentrating for a moment before standing up. "Kisaragi Aine, right?" He gasps in surprise as she speaks his name. "Your future is a difficult one. Faced with a fork in your path, you'll have to choose. Would you rather make the one you love happy or save yourself? The choice is yours but it'll decide your entire future." She smiles mysteriously.

Aine understood nothing of what she just said.

He doesn't have a chance to reply because she then turns to Reiji, taking his outstretched hand. She has barely closed her eyes before they shoot open again, and she gasps, though her face doesn't betray her emotions. Her voice, however, shakes.

"Kotobuki Reiji... A devil out there has something against you. Your life will be a short one, cursed with death. Though short, it has a chance of being happy as long as you live it to the fullest. Your chances of surviving are slim, but not impossible given the right situation." She shakes her head gravely as she stands up, both boys gaping at her dark words.

"I'm sorry, my child. I wish you luck." With that, Haruka disappears through the gates, Tomo on her heels.

Aine and Reiji stand there shell-shocked, watching as she leaves. As Haruka and Tomo disappear around the corner, Aine's attention is caught by a sudden thud, and the unconscious body of his friend on the ground as he turns around.

"Reiji!"

...

Reiji often fainted at random times and was prone to getting injured or heart attacks. He was lucky so far that none of his situations had been fatal, but as he grew older, they became worse and worse.

The problem was, the doctors couldn't find anything _wrong_ with him.

Aine was the only one who knew. It had something to do with what the witch Haruka had told them years ago. It was a memory that Reiji had forgotten, but Aine remembered.

He bites his lip harshly before pushing open the door to Reiji's hospital room.

The brunette lies on the bed, wrapped in a body cast and in a coma from the accident he had gotten into recently. It was unnatural how prone to harmful situations Reiji was. If he played soccer, he always seemed to get hit in the head by the ball on accident. If he was reading in the library, shelves of books seemed to tumble down on to him. It was unnatural.

It was _supernatural_.

It must have been the curse of the devil that Haruka mentioned.

It frustrates Aine to no end about how he had no way to help his friend... no, his crush.

They had known each other since elementary school, and had stuck together ever since. Now in Saotome Academy together, Aine realized that he had developed feelings for his best friend over the years. He would confess but...

He didn't want to ruin their friendship, their short and soon to fade friendship when Reiji's curse finally caught up to him.

Tears sparkling in his eyes, he turns and races out of the room.

...

It's been three years since he had last spoke to Reiji. Ten since they met _her_. Aine muses over that fact as he stands on the beach, watching the sun fade beyond the horizon.

It wasn't that he didn't want to. But... Reiji had never woken up from his coma.

The doctors were giving up on him. His family was ready to take him off life support.

The nineteen year old alumni of Saotome Academy lowers his eyes to gaze at the sand. _But he wasn't ready to let his first love go_.

"Are you ready to face the fork in your path?" Haruka's voice seems to whisper in his ear, carried by the wind.

 _Yes._ He slowly closes his eyes, his mind set.

That night, a young man with cyan hair is found washed up on the beach in a coma, and in the hospital, a brunette opens his space gray eyes.


	2. Part 2

Part Two

The first time Reiji meets Ai, he feels a sting of nostalgia.

He has kept it to himself for a long time, but there are certain chunks of his memory missing from before he woke up from his coma six years ago.

What he couldn't remember weren't events. They seemed to revolve around a certain person, though his face and name were both unknown to Reiji. All of his memories regarding that person seemed to have vanished, though he seemed to have been an important person to him.

Yet, when he meets Ai, he can't help but be reminded of that someone, yet he just doesn't know why. Using knowing his fellow members of the new Quartet Night better as an excuse, he decides to attach himself onto the mysterious cyan haired teen, hoping to trigger some of his memories.

What he doesn't expect is to fall for the robotic idol, Mikaze Ai.

...

The first time Ai meets Reiji, he feels emotions that aren't programmed in him.

 _Are these Aine's feelings?_ He wonders, narrowing his eyes at the brunette.

However, just as suddenly as they came, the feelings dissipate... along with Aine's consciousness. Outwardly, Ai is simply stoic, though he doesn't show his inward turmoil. _How did Aine simply just disappear?!_ His brain activity was linked with Aine's, so the only way Aine's consciousness would disappear was if he either died or his consciousness left his body.

Ai is deep in thought. Should he tell the professor about what had occurred? The robot part of him tells him "yes," to obey his purpose. After all, he was built to quicken Aine's revival. He should tell the professor what happened to Aine, right?

But the part of him that identifies himself as "Mikaze Ai" tells him "no." If he told the professor, there was a 75.1% chance that he would be shut down since if Aine wasn't connected to him anymore, he was useless.

He didn't want that. Especially now that he is curious of the feelings that Aine felt towards this Kotobuki Reiji. Ai had a craving for knowledge. And he wanted to know. He decides that he would keep Aine's condition to himself for a while.

He acts cold to the brunette that attaches himself to him, though he allows it, for his research. Just until he finds out how to identify Aine's feelings, he tells himself.

What he doesn't expect is to fall for the annoying brunette, Kotobuki Reiji.

...

When Aine awakens, he isn't in Ai's mind anymore. His consciousness is floating in midair, like a ghost. He glances down at his body, sound asleep in coma.

Why did he detach himself from Ai's brain again? He tries to remember, and then it hits him like a truck. _Reiji_. It pains him too much to see Reiji now, especially since he has forgotten about Aine's existence.

It's for the best, he tells himself. By putting himself in a coma and erasing Reiji's memories of his existence, Reiji's curse of death has been broken. It's for the best.

He knows, but why does he feel such pain?

He also didn't want to burden Ai with his feelings for Reiji invading the already confused robot's mind. He felt bad for the poor robot, who was forced to live a life in order for him to wake up. Hopefully, if Aine was detached from him, Ai could live a life of his own.

It's for the best. His ethereal form closes his eyes. He wouldn't bother either Ai or Reiji anymore. He will just wait here in the lab, until his body finally breaks down and his consciousness fades.

However, a year later, he finds himself drifting towards that Shining Master Course Dormitory, to check on Ai, he tells himself as he hesitantly floats down the street, invisible to everyone. To see if he was doing alright by himself.

Oh, who is he kidding?

He wants to see Reiji.

...

When he arrives, he floats through the dorms, looking around for traces of Ai or Reiji. There are more people here than when Ai first arrived, he notes.

In the hallway, he finds a redhead running towards a grumpy looking silverette, who Aine faintly recognizes. Kurosaki Ranmaru. If he remembers correctly, he is another member of Reiji's new idol group, Quartet Night.

"Kurosaki-senpai!" The redhead halts in front of Ranmaru, panting. "Do you know where Rei-chan is? Tokiya and I want to show him our newest piece!"

Ranmaru rolls his eyes, before turning away and heading down the hall, bored with the conversation. However, his answer lingers behind. "Don't bother. Last I heard, he went with Ai to the park. He's never going to listen to you with Ai around."

The redhead seems a bit disappointed, but let's out a "oh" of understanding. He rushes back in the direction he came, where a bluenette was waiting for him.

"Rei-chan went with Ai-senpai to the park." He announces, a bit down. The bluenette smiles slightly, though rather fondly.

"Don't worry, Otoya. We can show him 'Roulette' later. Besides, Kotobuki-san and Mikaze-san don't go out very often. Let them be."

"Ok..." The two's voices fade down the hallway, while Aine stiffens.

It can't be... Why Reiji and Ai went to the park was still rather vague, but from the conversation Aine just witnessed, he could feel a few implications.

One of which he didn't really want to believe.

He rushes out of the dorms in the direction of the park.

...

It's spring, the season for cherry blossoms. Delicate sakura petals drift down from the trees all around the park where a disguised brunette looks up with a smile at the arrival of a younger cyan-haired male.

"Why did you call me out here, Reiji?" The cyanette's hair is down and a hat along with fake glasses conceal his identity. Though his tone seems annoyed, a bit of fondness shows through his emotionless eyes. Something that only Reiji can pick out.

"Don't be like that, Ai-Ai!" The brunette whines, even though he knows that Ai isn't really annoyed. He takes the younger male's hand in his own. "We rarely are allowed to go out! And you're always so busy! Since it's our day off, let's enjoy ourselves a bit, okay?"

Ai sighs, ever the tsundere even as a small smile graces his lips. "Fine." Reiji is about to cheer when he adds, "Only if you buy me marine jelly. If you do, we'll go out on a date."

Reiji seems relieved at Ai's request. After all, the last time they went out, the price was that Reiji had to perfect the singing and choreography to "The Dice are Cast" in one day. It had been exhausting. "Of course, Ai-Ai! No problem!"

Aine watches them as they leave the park, Reiji chattering happily on as Ai quietly lets him with a fond smile. He feels a sting of jealousy and hurt, but he smiles bittersweetly at the scene before him.

"Do you regret your choice?" Somehow, he is not surprised when Haruka appears besides him, watching the couple alongside him. It isn't even surprising that she knows that he is there.

"No." He turns his gaze away as Reiji leans over to press a chaste kiss to Ai's lips under the sakura trees. He meets the sparkling goldenrod eyes of the woman who changed his life. "After all..."

"It's for the best."

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 **A/N:** Ok. Sorry if there were too many scene breaks.

I'm not a big fan of ReiAi, but I found the prompt and I immediately thought that this was quite perfect.

The original prompt credited to OTP Prompts: Imagine Person A being cursed from birth to die an early death. Person B, who is madly in love with Person A, chooses to change Person A's fate in exchange for Person A's memories of Person B. Person B becomes invisible as well. Years later, Person A has fallen for Person C while Person B lingers on, watching over them.

I tweaked a few details, but I mostly follow the prompt.

I hope I fully conveyed Aine's pain. Please review! It will make my day if this touched someone's heart.

See you all next time (probably in Hearts Intertwined)!

~Crystal


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